Systems and methods for power management and control

ABSTRACT

Systems and methods directed to improved battery management, motor control, energy storage and battery charging. The systems and methods enable vehicle electrification and provides a paradigm changing platform that enables integration of battery management, charging and motor controls with means to manage regenerative braking, traction and handling. In embodiments, systems and methods are directed to a unified modular battery pack system having a cascaded architecture comprising an integrated combination of a networked low voltage converter/controller with peer-to-peer communication capability, embedded ultra-capacitor or other secondary energy storage element, battery management system and serially connected set of individual cells as the fundamental building block.

CROSS-REFERENCE TO RELATED APPLICATIONS

The subject application is a continuation of U.S. patent applicationSer. No. 17/020,319, filed Sep. 14, 2020, which is a continuation ofU.S. patent application Ser. No. 16/681,429, filed Nov. 12, 2019, nowU.S. Pat. No. 10,821,843, which is a continuation of PCT PatentApplication No. PCT/US19/23695, filed Mar. 22, 2019, which claimspriority to U.S. Provisional Patent Application No. 62/646,861, filed onMar. 22, 2018, all of which are incorporated by reference herein intheir entireties for all purposes.

FIELD

The present disclosure relates to electric power management and controlof battery systems, and more particularly to systems and methods thatfacilitate improved battery management, motor control, energy storage,and battery charging for electric vehicles and other stationaryapplications.

BACKGROUND

Today's automobile technology, as evolved over the past century, ischaracterized, amongst many things, by an interplay of motors,mechanical elements, and electronics. These are the key components thatimpact vehicle performance and driver experience. Motors are of thecombustion or electric type and one usually finds one motor per car,exceptions being cars with hybrid drivetrains, featuring a combinationof a combustion engine with one or two electric motors, or performanceoriented electric vehicles that are outfitted with two motors. In almostall cases the rotational energy from the motor(s) is delivered via a setof highly sophisticated mechanical elements, such as clutches,transmissions, differentials, drive shafts, torque tubes, couplers, etc.These parts control to a large degree torque conversion and powerdistribution to the wheels and are key elements to define theperformance of the car. They also impact road handling. Over the yearsindividual car manufacturers have highly optimized these mechanicalparts to provide better performance, higher fuel efficiency andultimately differentiation in the market place. On the control side,apart from driver comforts such as entertainment, navigation and humanmachine interface elements, there are typically only a few clusters ofspecialty electronics hardware and embedded software thatcontrol/optimize motors, clutch/transmission operation and roadholding/handling.

Today's electric automobiles or vehicles (EVs) have largely adopted mostof the hundred-year old design paradigm of a combustion vehicle, withthe obvious substitutions of batteries, charging systems and electricmotors for the usual gas tank, fuel pumps/injectors and combustionengine. While the control electronics are adapted to the difference incomponents, it is important to realize that most of the mechanicaldrivetrain parts described above are still there (see, e.g., FIGS. 1 and2 ). This is to say that the overall design philosophy of current EVshas moved little beyond the conventional paradigm. As such, the truepotential of electrification is not being realized.

An EV comprises various electrical systems that are related to thedrivetrain including, among others, the battery, the charger and motorcontrol. A short inventory of the current capabilities and shortcomingsof these electrical systems include:

Conventional Battery Design

At the moment, high voltage battery packs are typically organized in aserial chain of lower voltage battery modules. Each such module isfurther comprised of a serially connected set of individual cells and asimple embedded battery management system to regulate basic cell relatedcharacteristics, such as state of charge and voltage. Electronics withmore sophisticated capabilities or some form of smart interconnectednessis absent. As a consequence, any monitoring or control function ishandled by a separate system, which, if at all present elsewhere in thecar, lacks the ability to monitor individual cell health, state ofcharge, temperature and other performance impacting metrics. There isalso no ability to adjust power draw per individual cell in any form.Some of the major consequences are: (1) the weakest cell constrains theoverall performance of the entire battery pack, (2) failure of any cellor module leads to a need for replacement of the entire pack, (3)battery reliability and safety are considerably reduced, (4) batterylife is limited, (5) thermal management is difficult, (6) battery packsalways operate below maximum capabilities, (7) sudden inrush into thebattery packs of regenerative braking derived electric power cannot bereadily stored in the batteries and will require dissipation via a dumpresistor.

Current Charger Design

Charging circuits are typically realized in separate on-board systems.They stage power coming from outside the EV in the form of an AC signalor a DC signal, convert it to DC and feed it to the battery pack(s).Charging systems monitor voltage and current and typically supply asteady constant feed. Given the design of the battery packs and typicalcharging circuits, there is little ability to tailor charging flows toindividual battery modules based on cell health, performancecharacteristics, temperature, etc. Charging cycles are also typicallylong as the charging systems and battery packs lack the circuitry toallow for pulsed charging or other techniques that would optimize thecharge transfer or total charge achievable.

Current Motor Control Design

Conventional controls contain DC to DC conversion stages to adjustbattery pack voltage levels to the bus voltage of the EV's electricalsystem. Motors, in turn, are then driven by simple two-level multiphaseconverters that provide the required AC signal(s) to the electric motor.Each motor is traditionally controlled by a separate controller, whichdrives the motor in a 3-phase design. Dual motor EVs would require twocontrollers, while EVs using four in-wheel motors would require 4individual controllers. The conventional controller design also lacksthe ability to drive next generation motors, such as switch reluctancemotors (SRM), characterized by higher number of pole pieces. Adaptationwould require higher phase designs, making the systems more complex andultimately fail to address electric noise and driving performance, suchas high torque ripple and acoustical noise.

In view of the foregoing limitations, systems and methods thatfacilitate improved battery management, motor control, power storage,and battery charging are desirable to address the above notedshortcomings and provide a paradigm changing platform.

SUMMARY

The embodiments of the present disclosure are directed to systems andmethods that facilitate improved battery management, motor control,energy storage and battery charging. As such, the systems and methodsprovided herein enable realization of the true potential of vehicleelectrification and provide a paradigm changing platform thatintelligently integrates battery management, charging and motor controlswith means to manage regenerative braking, traction and handling.

Exemplary embodiments of the present disclosure are preferably directedto a unified modular battery pack system having a cascaded architecturecomprising an integrated combination of a networked low voltageconverter/controller with peer-to-peer communication capability,embedded ultra-capacitor or other secondary energy storage element,battery management system and serially connected set of individual cellsas the fundamental building block. An interconnected assembly of suchintelligent battery modules becomes effectively a smart electrical“neural network” and the replacement for: (1) a charging system, (2)battery management modules, (3) DC to DC converter, and (4) motorcontroller(s).

This modular smart battery pack system is not only combinable withconventional EV motors and drive trains, it is combinable with newin-wheel EV motors being developed for use in future EVs.

In exemplary embodiments provided herein, the electronics of eachmodular smart battery pack are based on a multilevel controller, whichin certain exemplary embodiments is preferably a bi-directionalmultilevel hysteresis controller, combined with temperature sensors andnetworking interface logic. This design provides a long list ofadvantages: (1) improved battery utilization through individualswitching of modules based on their age, thermal condition andperformance characteristics; (2) reduced thermal losses in cells throughcareful power consumption or power generation balancing; (3) slowed cellaging through better individual thermal management and filtering ofhigh-order current harmonics; (4) capability of granular monitoring ofbattery health and early warning of servicing need; (5) fail-safe andredundant design capable of maintaining drivability, even underindividual module failure; (6) higher efficiency and better economicsthrough utilization of new semiconductor technologies operating at lowercomponent voltages to reduce power losses and cost; (7) software basedoptimization of topologies and control methods to adapt to differentvehicle characteristics; (8) close to full recuperation of energy fromregenerative braking and fast response on acceleration by virtue ofembedded ultra-capacitors; (9) integrated on-board optimized chargingdue to individual cell load balancing and monitoring, includingultra-fast pulsed charging driven by intelligent controller circuitry;(10) reduced electromagnet interference and sensitivity of the circuittopology; (11) adaptive neural-net based coordination between modules toenhance overall system performance, response time, thermal managementand collective system efficiency; (12) elimination of mechanicaldrivetrain components and associated losses when combined with in-wheelmotors; (13) reduction of overall drivetrain magnetic and electriclosses; (14) increased power density when used with in-wheel motors;(15) reduction of torque ripple and increased passenger comfort due toreduced electrical and mechanical noise from refined motor control andelectrical filtering; (16) ability to adapt to and be optimized for allcurrent and next generation motor designs; (17) reduction in spaceproviding more room for passengers/cargo/additional batteries (morerange); (18) reduction in weight providing for better performance,higher vehicle efficiency, farther driving range; (19) superior handlingand better traction when combined with in-wheel motors; (20) universalbuilding block, adaptable for use from small passenger cars to largebuses and commercial trucks; (21) software based differentiation ofvehicle characteristic instead of via traditional mechanical componentdesigns.

Other systems, methods, features and advantages of the exampleembodiments will be or will become apparent to one with skill in the artupon examination of the following figures and detailed description.

BRIE DESCRIPTION OF THE DRAWINGS

The details of the example embodiments, including structure andoperation, may be gleaned in part by study of the accompanying figures,in which like reference numerals refer to like parts. The components inthe figures are not necessarily to scale, emphasis instead being placedupon illustrating the principles of the disclosure. Moreover, allillustrations are intended to convey concepts, where relative sizes,shapes and other detailed attributes may be illustrated schematicallyrather than literally or precisely.

FIG. 1 illustrates a simplified schematic of the power electroniccircuit and electric motor of a conventional battery electric vehicle

FIG. 2 illustrates a schematic of a power electronic circuit andelectric motor for a battery electric vehicle according to embodimentsof the present disclosure having a unified modular system with cascadedarchitecture including an intelligent modular AC battery pack comprisinga series connection of intelligent low voltage battery modules.

FIGS. 3A through 3I illustrate schematics showing the power electroniccircuit according to embodiments of the present disclosure as anintelligent, modular representation of the conventional high voltagepower electronic circuit for a battery electric vehicle shown in FIG. 1; FIG. 3A shows the high voltage battery pack comprising a serial chainof low voltage battery modules; FIG. 3B shows each battery modulecomprising a series connection of lower voltage battery cells and anintegrated battery management or control system; FIG. 3C shows the highvoltage DC/AC converter split into multiple low voltage DC/AC convertersin series; FIG. 3D shows an individual low voltage DC/AC converterintegrated within an individual battery module; FIG. 3E shows an ultra-or super-capacitor integrated within an individual battery module tointermittently store in-rush of braking power; FIG. 3F shows an highvoltage intelligent modular AC battery pack comprising a seriesconnection of lower voltage intelligent battery modules integrated withbattery management or control systems, low voltage converters andultra-capacitors; FIGS. 3G and 3H shows the DC/DC converter removed fromthe power electronic circuit; and FIG. 3I shows the AC/DCconverter/charger removed from the power electronic circuit.

FIG. 4 illustrates a perspective view conceptual representation of anintelligent battery module comprising a battery integrated with abattery management and control system, a low voltage converter and anultra-capacitor according to embodiments of the present disclosure.

FIG. 5 illustrates a schematic diagram of an intelligent battery moduleaccording to embodiments of the present disclosure coupled to a batterymodule control system (or local electronic control unit (ECU)) and amaster control system (or master ECU).

FIG. 6 illustrates a schematic diagram of multiple intelligent modularAC battery packs according to embodiments of the present disclosurecoupled to a three phase motor and a charging coupling for coupling to asingle or three phase grid or power source.

FIGS. 7A and 7B illustrate graphs of typical waveforms of outputvoltages for one (1) intelligent battery module (FIG. 7A) and one (1)phase of the intelligent modular AC battery pack with six (6)intelligent battery modules connected in series in each phase (FIG. 7B).

FIGS. 8A, 8B, 8C and 8D illustrate graphs showing the principle of phaseshifted carrier technique.

FIG. 9 illustrates a schematic of a functional diagram of voltage levelselector of a nine-level four-quadrant hysteresis controller.

FIGS. 10A, 10 B and 10C illustrates graphs showing the operation of anine-level four-quadrant hysteresis controller; FIG. 10A illustrates thecurrent control error I_(ERROR), as a difference between I_(REAL) andI_(REF); FIG. 10 B illustrates the reference current I_(REF) and realcurrent I_(REAL) in motor phase; FIG. 10C illustrates the converteroutput voltage V_(OUT).

FIG. 11 illustrates a functional diagram of a 9-level, 4-quadranthysteresis current controller with state of charge (SOC) balancing andzero state rotation.

FIG. 12 illustrates a functional diagram of an intelligent batterymodule rotation controller.

FIG. 13 illustrates a functional diagram of a di/dt Estimator.

FIGS. 14A and 14B illustrate functional diagrams of −0 VDC Rotation(FIG. 14A) and +0 VDC Rotation (FIG. 14B) blocks.

FIGS. 15A and 15B illustrate functional diagrams of +1 VDC Rotation(FIG. 15A) and −1 VDC Rotation (FIG. 15B) blocks.

FIGS. 16A, 16B, 16C and 16D illustrate functional diagrams of 0 VDCRotation Generator (FIG. 16A), 1 VDC Rotation Generator (FIG. 16B), 2VDC Rotation Generator (FIG. 16C) and 3 VDC Rotation Generator (FIG.16D).

FIG. 17 illustrates a schematic diagram of a centralized connection ofall intelligent modules to a master ECU for state of charge (SOC)balancing.

FIG. 18 illustrates a flow diagram of structure power flow management inthe intelligent battery module.

FIG. 19 illustrates a circuit diagram showing the topology of theintelligent battery module and currents in node 1.

FIGS. 20A and 20B illustrate graphs of typical waveforms of currents inthe intelligent battery module when the supercapacitor module operatesas an active filter.

FIG. 21 illustrates a single-phase intelligent battery pack connected toa single-phase load.

FIG. 22 illustrates a three-phase intelligent battery pack connected toSwitched Reluctance Motor.

It should be noted that elements of similar structures or functions aregenerally represented by like reference numerals for illustrativepurpose throughout the figures. It should also be noted that the figuresare only intended to facilitate the description of the preferredembodiments.

DETAILED DESCRIPTION

The following embodiments are described in detail to enable thoseskilled in the art to make and use various embodiments of the presentdisclosure. It is understood that other embodiments would be evidentbased on the present disclosure, and that system, process, or changesmay be made without departing from the scope of the present embodiments.

The embodiments of the present disclosure are directed to systems andmethods that facilitate improved battery management, motor control,energy storage and battery charging. As such, the systems and methodsprovided herein enable realization of the true potential of vehicleelectrification and provide a paradigm changing platform thatintelligently integrates battery management, charging and motor controlswith means to manage regenerative braking, traction and handling.

Exemplary embodiments of the present disclosure are preferably directedto a unified modular battery pack system having a cascaded architecturecomprising an integrated combination of a networked low voltageconverter/controller with peer-to-peer communication capability,embedded ultra-capacitor, battery management system and seriallyconnected set of individual cells as the fundamental building block. Aninterconnected assembly of such intelligent battery modules becomeseffectively a smart electrical “neural network” and the replacement for:(1) a charging system, (2) battery management modules, (3) DC to DCconverter, and (4) motor controller(s).

This modular smart battery pack system is not only combinable withconventional EV motors and drive trains, it is combinable with newin-wheel EV motors being developed for use in future EVs.

In exemplary embodiments provided herein, the electronics are based on abi-directional multilevel controller, combined with temperature sensorsand networking interface logic. In certain exemplary embodiments thebi-directional controller is a bi-directional multilevel hysteresiscontroller.

Turning in detail to the figures, a simplified schematic of aconventional power electronic circuit 10 and electric motor 70 is shownin FIG. 1 . As shown in FIG. 1 , the power electronic circuit 10typically includes a charger 20 comprising an AC-DC converter, a highvoltage battery pack 30 electrically coupled to the charger 20, a DC-DCconverter 40 electrically coupled to the high voltage battery pack 30,an DC-AC converter 50 electrically coupled to the DC-DC converter 40,and an electric motor 60 electrically coupled to the DC-AC converter 50.

Conventional high voltage battery packs 30 are typically organized in aserial chain of low voltage battery modules 32 (see, e.g., FIGS. 3A and3B). Each such module 32 is further comprised of a serially connectedset of individual lower voltage cells 34 and a simple embedded batterymanagement system 36 to regulate basic cell related characteristics,such as state of charge and voltage (see, e.g., FIG. 3B). Electronicswith more sophisticated capabilities or some form of smartinterconnectedness is absent. As a consequence, there is also no abilityto adjust power draw per individual cell 34 in any form. Some of themajor consequences are: (1) the weakest cell constrains the overallperformance of the entire battery pack, (2) failure of any cell/moduleleads to a need for replacement of the entire pack, (3) batteryreliability and safety are considerably reduced, (4) battery life islimited, (5) thermal management is difficult, (6) packs always operatebelow maximum capabilities, (7) sudden inrush of regenerative brakingderived electric power cannot be readily stored in the batteries.

Conventional charging circuits or systems, such as those represented bythe charger 20, are usually realized in separate on-board systems. Suchcharging systems stage power (AC or DC signal) coming from outside theEV and convert it to DC and feed it to the battery pack(s) 30. Thecharging systems monitor voltage and current and typically supply asteady constant feed. Given the design of the batteries and typicalcharging circuits, there is little ability to tailor charging flows toindividual battery modules 32 of the battery pack 30 based on cellhealth, performance characteristics, temperature, etc. Charging cyclesare also typically long as the charging systems and battery packs 30 andindividual modules 32 lack the circuitry to allow for pulsed charging orother techniques that would optimize the charge transfer or total chargeachievable.

Conventional controls contain DC to DC conversion stages (see, e.g.,DC-DC converter 40) to adjust the voltage levels of the battery pack 30to the bus voltage of the electrical system of the EV. Motors, such asmotor 60, in turn, are then driven by simple two-level multiphaseconverters (see, e.g., DC-AC converter 50) that provide the required ACsignal(s) to the electric motor 60. Each motor is traditionallycontrolled by a separate controller, which drives the motor in a 3-phasedesign. Dual motor EVs would require two controllers, while EVs usingfour in-wheel motors would require 4 individual controllers. Theconventional controller design also lacks the ability to drive nextgeneration motors, such as, e.g., switch reluctance motors (SRM), whichare characterized by a higher number of pole pieces. Adaptation wouldrequire higher phase designs, making the systems more complex andultimately fail to address electric noise and driving performance, suchas high torque ripple and acoustical noise.

In contrast to the complex power electronic circuit 10 of conventionalEVs, exemplary embodiments provided herein as illustrated in FIG. 2 ,replace the charging system 20, battery management modules, DC to DCconverter 40, and motor controller(s) 50 with an intelligent or smartmodular AC battery pack 130 comprising an interconnected assembly ofintelligent or smart battery modules 132 effectively providing a smartelectrical “neural network”.

Turning to FIGS. 3A through 3I, a series of schematics illustratingsimplification of the complex high voltage power electronic circuit 10for conventional EVs shown in FIG. 1 to an intelligent or smart batterypack 130, as shown in FIG. 2 , comprising an interconnected assembly ofintelligent battery modules 132 according to exemplary embodiments ofthe present disclosure. As shown in FIG. 3A, the high voltage batterypack 30 comprising a serial chain of lower voltage battery modules 32,each of which comprises a series connection of lower voltage batterycells 34 and an integrated battery management and control system 36 asshown in FIG. 3B. The high voltage DC/AC converter 50 can be split intomultiple low voltage DC/AC converters 52 connected in series as shown inFIG. 3C. Each of the individual low voltage DC/AC converters 52 can beintegrated within an individual battery module to form a smart orintelligent battery module 132 as shown in FIG. 3D. To intermittentlystore an in-rush of braking power, FIG. 3E shows an ultra-capacitor 38integrated within an individual intelligent battery module 132 (seealso, e.g., FIG. 4 ). As depicted in FIG. 3F, a high voltage intelligentbattery pack 130 comprises an interconnected assembly of intelligentbattery modules 132. As shown in FIGS. 3G and 3H, the high voltageintelligent battery pack 130 effectively eliminates the need for theDC/DC converter 40. As shown in FIGS. 3H and 3I, the high voltageintelligent battery pack 130, which is effectively an intelligentmodular AC battery pack 130, effectively eliminates the need for theAC/DC converter/charger 20.

Intelligent Battery Module Architecture

FIGS. 4 and 5 show a perspective view and a diagram, respectively, of anintelligent battery module 132 with the regenerativebraking/acceleration capability using supercapacitors (or ultracaps). Ithas three main components: the battery 32 with a BMS 36, thesupercapacitor module 38 with bidirectional DC-DC converter based onMOSFET Transistors (MOSFETs) S1 and S2 with supercapacitor bank CSC andcoupling inductor LC, and the output converter 52 based on four-quadrantH-bridge topology with four MOSFETs S₃-S₆. As shown in FIG. 5 , theintelligent battery module 132 is coupled to a battery module controlsystem 200 (or local electronic control unit (ECU)) and a master controlsystem 210 (or master ECU).

ACi Battery Pack Principle of Operation

FIG. 6 depicts a topology of 3-phase ACi battery pack (130A, 130B, 130C)connected to the motor 60 and comprising N intelligent battery modulesconnected in series in each phase. Each intelligent battery module inFIGS. 5 and 6 can generate three different voltage outputs, +V_(dc), 0,and −V_(dc) by connecting the DC-voltage (of battery) VDC to the ACoutput by different combinations of the four switches, S₃, S₄, S₅, andS₆. To obtain +V_(dc), switches S₃ and S₆ are turned on, whereas −V_(dc)can be obtained by turning on switches S₄ and S₅. By turning on S₃ andS₅ or S₄ and S₆, the output voltage is 0. The AC outputs of each of thedifferent output converter levels are connected in series such that thesynthesized voltage waveform is the sum of the inverter outputs. Thenumber of output phase voltage levels m in ACi battery pack is definedby m=2s+1, where s is the number of intelligent battery modules. Anexample phase voltage waveform for pulse width modulation (PWM)modulated 13-level ACi battery pack with six intelligent battery modulesconnected in series in each phase is presented in FIG. 7B and an outputvoltage of one of the intelligent battery modules 132 is shown in FIG.7A.

The ACi battery pack can also serve as a rectifier/charger for thebatteries of the intelligent battery modules 132 while the vehicle isconnected to an AC supply as shown in FIG. 6 .

The switching signals S₃-S₆ (See FIGS. 5 and 6 ) for the switches S₃-S₆of the output converter 152 in each intelligent battery module 132 maybe generated in different ways depending on the flexibility andrequirements of the adopted control hardware. One approach is to usespace vector modulation or sine PWM to generate the reference voltagefor each phase of the intelligent battery module 132. The switchingsignals for each intelligent battery module's output converter may thenbe generated using phase shifted carrier technique. This techniqueensures that the cells are continuously rotated, and the power is almostequally distributed among them.

Modulation of Output Voltage in ACi Battery Pack—Multi-Level PWMModulation

The principle of the phase shifted technique is to generate themultilevel output PWM waveform using incrementally shifted two-levelwaveforms. Therefore, an N-level PWM waveform is created by thesummation of N−1 two-level PWM waveforms. These two-level waveforms aregenerated by comparing the reference waveform to triangular carriersthat are incrementally shifted by 360°/(N−1). A 9-level example is shownin FIG. 8A. The carriers are incrementally shifted by 360°/(9−1)=45° andcompared to the reference waveform. The resulted two-level PWM waveformsare shown in FIG. 8C. These two-level waveforms may be used as the gatesignals for the output converter (H-Bridge) MOSFETs in each intelligentbattery module. For our 9-level example, which comprises four H-bridges,the 0° signal is used for S₃ and 180° signal for S₆ of the first module,the 45° signal is used for S₃ and 225° signal for S₆ of the secondmodule, and so on. Note that in all H-bridges, the signal for S₄ iscomplementary to S₃ and the signal for S₅ is complementary to S₆ alongwith certain dead-time to avoid shoot through of each leg.

Depending on the resources and limitations of the hardware that is usedto implement the modulation, an alternative is to generate the negativereference signal along with the first (N−1)/2 carriers. The 9-levelexample is shown in FIG. 8B. In this case, the 0° to 135° PWM signalsare generated by comparing V_(ref) to the corresponding carriers and the180° to 315° PWM signals are generated by comparing −V_(ref) to carriersof 0° to 135°. However, the logic of the comparison in the latter casemust be reversed.

Other techniques such as a state machine decoder may also be used togenerate the gate signals for the H-bridges.

Modulation of Output Voltage in ACi Battery Pack—Multi-Level HysteresisControl

Another approach to creating the switching signals S₃-S₆ (See FIGS. 5and 6 ) for the output converter's switches in each intelligent batterymodule is a multi-level hysteresis control technique. This controlmethod can be used with any type of motor and is very efficientespecially for switched reluctance motor (SRM) drives.

The multi-level hysteresis control is described here for only one ofthree phases of the three phase ACi battery pack. In case of PMSM motor,three controllers have to be used together with additional circulationcurrent reduction block (not described here). For a SRM motor a numberof controllers can be more than three and there is no need in acirculation current reduction block.

For 9-level ACi battery pack (see FIG. 6 ) comprising four intelligentbattery modules 132 connected in series in each phase, all possibleswitching states for output converter's switches with correspondingoutput voltage levels are presented in Table 1. Only switching statesfor odd switching elements (MOSFETs S₃ ^(N) and S₅ ^(N), where N=1, 2,3, 4 is a number of intelligent battery module) are presented in thistable. In fact, to avoid a short circuit of the filtering capacitorC_(F) ^(N) only one switch in a half-bridge of output H-bridge convertercan be ON (in conducting mode) at any moment of time. Thus, the controlsignals for even switching elements (MOSFETs S₄ ^(N) and S₆ ^(N), whereN=1, 2, 3, 4 is a number of intelligent battery module) can be easilyobtained by reversing the states of odd switching elements of the samehalf-bridge. For example, if S₃ ^(N)=1 and S₅ ^(N)=0, then S₄ ^(N)=0 andS₆ ^(N)=1.

TABLE 1 Switching States of 9-level 4-quadrant Multilevel CascadedConverter Output Switching States Voltage S₃ ¹ S₅ ¹ S₃ ² S₅ ² S₃ ³ S₅ ³S₃ ⁴ S₅ ⁴ −4VDC 0 1 0 1 0 1 0 1 −3VDC −3VDC1 1 1 0 1 0 1 0 1 0 0 0 1 0 10 1 −3VDC2 0 1 1 1 0 1 0 1 0 1 0 0 0 1 0 1 −3VDC3 0 1 0 1 1 1 0 1 0 1 01 0 0 0 1 −3VDC4 0 1 0 1 0 1 1 1 0 1 0 1 0 1 0 0 −2VDC −2VDC12 1 1 1 1 01 0 1 0 0 0 0 0 1 0 1 −2VDC13 1 1 0 1 1 1 0 1 0 0 0 1 0 0 0 1 −2VDC14 11 0 1 0 1 1 1 0 0 0 1 0 1 0 0 −2VDC23 0 1 1 1 1 1 0 1 0 1 0 0 0 0 0 1−2VDC24 0 1 1 1 0 1 1 1 0 1 0 0 0 1 0 0 −1VDC −1VDC1 0 1 1 1 1 1 1 1 0 10 0 0 0 0 0 −1VDC2 1 1 0 1 1 1 1 1 0 0 0 1 0 0 0 0 −1VDC3 1 1 1 1 0 1 11 0 0 0 0 0 1 0 0 −1VDC4 1 1 1 1 1 1 0 1 0 0 0 0 0 0 0 1 0 1 1 1 1 1 1 11 0 0 0 0 0 0 0 0 +1VDC +1VDC1 1 0 1 1 1 1 1 1 1 0 0 0 0 0 0 0 +1VDC2 11 1 0 1 1 1 1 0 0 1 0 0 0 0 0 +1VDC3 1 1 1 1 1 0 1 1 0 0 0 0 1 0 0 0+1VDC4 1 1 1 1 1 1 1 0 0 0 0 0 0 0 1 0 +2VDC +2VDC12 1 1 1 1 1 0 1 0 0 00 0 1 0 1 0 +2VDC13 1 1 1 0 1 1 1 0 0 0 1 0 0 0 1 0 +2VDC14 1 1 1 0 1 01 1 0 0 1 0 1 0 0 0 +2VDC23 1 0 1 1 1 1 1 0 1 0 0 0 0 0 1 0 +2VDC24 1 01 1 1 0 1 1 1 0 0 0 1 0 0 0 +3VDC +3VDC1 1 1 1 0 1 0 1 0 0 0 1 0 1 0 1 0+3VDC2 1 0 1 1 1 0 1 0 1 0 0 0 1 0 1 0 +3VDC3 1 0 1 0 1 1 1 0 1 0 1 0 00 1 0 +3VDC4 1 0 1 0 1 0 1 1 1 0 1 0 1 0 0 0 +4VDC 1 0 1 0 1 0 1 0

Zero output voltage 0 VDC can be ensured if all cells operate at zerostate at the same time. This can be obtained bypassing the battery byswitching ON either both upper switches or both lower switches. Forinstance, for intelligent battery module 1: S₃ ¹=1, S₅ ¹=1, S₄ ¹=0, S₆¹=0 or S₃ ¹=0, S₅ ¹=0, S₄ ¹=1, S₆ ¹=1.

Both voltage levels −3 VDC and +3 VDC can be obtained using four variouscombinations ±3 VDC1, ±3 VDC2, ±3 VDC3, ±3 VDC4, where the last indexcorresponds to a number of intelligent battery module operating at zerostate, providing output zero voltage. In turn, each zero state can becoded using two mentioned above combinations of switching. Thus, thereare eight possible combinations of setting ±3 VDC output voltage level.

Similarly, both voltage levels −2 VDC and +2 VDC can be set by fivedifferent combinations ±2 VDC12, ±2 VDC13, ±2 VDC14, ±2 VDC23, ±2VDC24depending on which two intelligent battery modules operate at zerostate voltage. Taking into account a dual possibility of providing azero state, a total number of possible combinations for ±2 VDC is equalto ten.

Both voltage levels −1 VDC and +1 VDC can be obtained using four variouscombinations ±1 VDC1, ±1 VDC2, ±1 VDC3, ±1 VDC4. The last indexcorresponds to a number of intelligent battery modules operating at ±1VDC level. Again, each zero state is obtained dually. Thus, like for ±3VDC level, there are eight possible combinations of providing ±1 VDCoutput voltage level.

Finally, the maximum voltage levels −4 VDC and +4 VDC can be provided atthe output of converter's phase, when all intelligent battery module inphase are operating at the same time. Thus, there is only one availablecombination of switching state for each these cases.

Selection of Voltage Levels in Hysteresis Control

Previously it was explained how every voltage level of nine-level ACibattery pack can be obtained by different switching combinations ofoutput converters of four intelligent battery modules 142. But the mostsignificant task for a multi-level hysteresis controller is theidentification of an appropriate output voltage level at any moment ofconverter operation based on a current feedback (motor phase) signalI_(REAL).

A block diagram of voltage level selector 300 is presented in FIG. 9 .The voltage level selector comprises two sum blocks Sum1 301 and Sum2307, five hysteresis blocks 302, 303, 304, 305 and 306, and one lookuptable for voltage level determination. The real feedback current signalI_(REAL) is subtracted from the reference current I_(REF) and thecurrent error signal I_(ERROR) as their difference comes to the input ofall five hysteresis blocks. Each of these blocks has different settingsof high (HB) and low (LB) boundary thresholds as presented in Table 2,where ΔI is preset value of maximum permitted current error. WhenI_(ERROR) reaches the corresponding high boundary (HB) of the hysteresisblock, its output value is set to “1” and remains at this level untilI_(ERROR) crosses its low boundary (LB). This will set “0” at the outputof hysteresis block and the output is maintained at this level untilI_(ERROR) reaches HB again. Thus, if low and high boundaries of fiveHysteresis Blocks are distributed within a range between −ΔI and +ΔI (asshown in Table 2), then the output of Sum2 will be varying from 1 to 6,depending on I_(ERROR) value. A look-up table 308 presented in FIG. 9 isused for determination of the required output voltage level based on thetotal state value (output of Sum2) of the hysteresis blocks and takinginto account a sign of the real (or reference) current derivative di/dt.As discussed below, a sign of di/dt can be determined as positive at themoment of time, when Sum2 reaches a value of 6, and will be changed to anegative one, when Sum2 becomes equal to 1.

TABLE 2 Current Threshold Levels for Hysteresis Blocks HysteresisCurrent Boundary threshold HB1 ΔI/5  LB1 −ΔI/5    HB2 2ΔI/5  LB2−2ΔI/5    HB3 3ΔI/5  LB3 −3ΔI/5    HB4 4ΔI/5  LB4 −4ΔI/5    HB5 ΔI LB5−ΔI  Switching Between Voltage Levels in Nine-Level Four-Quadrant HysteresisControl

A detailed description of the main principle of switching betweenvoltage levels in a nine-level four-quadrant hysteresis controltechnique for one phase of nine-level ACi battery Pack operation ispresented below.

In FIG. 10B the reference current I_(REF) (red trace) and real currentI_(REAL) (blue trace) in motor phase are presented together with fivepositive (HB1÷HB5) and five negative (LB1÷LB5) hysteresis boundaries(see Table 2 and FIG. 10A also), equally distributed between I_(REF)−ΔIand I_(REF)+ΔI and separated by ΔI/5 from each other (green traces). Thecurrent control error I_(ERROR), as a difference between I_(REAL) andI_(REF), and the converter output voltage V_(OUT) are presented in FIGS.10(a) and 10(c), respectively.

The initial status of V_(OUT) in the considered time window (from 23.06ms) was set previously by the control system at +4 VDC (where VDC=80V).At this voltage level the current I_(REAL) is rising up, and whenI_(ERROR) hits the first hysteresis boundary LB1 at point A (level−ΔI/5in FIG. 10(a)), the output states of first hysteresis block is changedfrom “1” to “0”, hence a sum at the output of Sum2 block is reduced byone from “6” to “5” (FIG. 9 ). And according to the table in FIG. 9 fordi/dt>0, the voltage V_(OUT) becomes +3 VDC.

From the beginning of considered time window and up to time t1 (FIG.10C), the current I_(REF) has a positive di/dt value and hysteresiscontroller shall operate with voltage levels presented in the secondcolumn of look-up table in FIG. 10C (di/dt>0). Starting from t1 thedi/dt sign of current I_(REF) is negative, but hysteresis controllerremains operating as for positive di/dt until time t2, when I_(ERROR)hits a fifth hysteresis boundary LB5 and Sum2=1. This event will switchan operation of hysteresis controller to the first column of the tablefor di/dt<0. In other words, a sign of di/dt can be determined asnegative at the moment (t2), when Sum2 reaches a value of “1” (and willbe changed to a positive, when Sum2 becomes equal to “6”). This logic isimplemented in di/dt estimator block, which will be presented asdescribed in the next sections of this document.

While V_(OUT) is at its maximum negative level −4 VDC, the currentI_(REAL) is falling down (FIG. 10(b)) and when it hits point F, whichcorresponds to the first hysteresis boundary HB1 in FIG. 10(a), theoutput states of first hysteresis block is changed from “0” to “1”,hence a sum at the output of Sum2 is increased by one from “1” to “2”(FIG. 9 ). And according to look-up table in FIG. 9 for di/dt<0, thevoltage V_(OUT) becomes −3 VDC. At point G, when I_(REAL) and I_(ERROR)reach HB2, Sum2 is incremented again and V_(OUT) becomes −2 VDC.

In the hysteresis control method provided herein, the maximum currenterror ΔI takes place only at the points where di/dt value of thereference current I_(REF) changes a sign. Beyond these critical points,the method works in such a way to minimize the current error I_(ERROR)at ΔI/5 as fast as possible at given parameters of the load.

Overall Method Description

The generalized functional diagram of a 9-level 4-quadrant hysteresiscurrent controller 500 with state of charge balancing and zero staterotation is presented in FIG. 11 . It includes the switch stage selector300, which functions as described earlier. The output signal of Sum2 inFIG. 9 is named as “Level” in FIG. 11 . This signal represents anumerical value for a general level (from 1 to 6) of a nine-levelhysteresis controller, which is used further in the method to select anappropriate output voltage level of intelligent battery module's outputconverter.

According to the look-up table in FIG. 9 , knowledge of the di/dt signis required to choose an appropriate output voltage level. As it wasmentioned earlier, a sign of di/dt can be determined as negative at themoment, when “Level” reaches a value of “1”, and will be changed to apositive, when “Level” becomes equal to “6”. This logic is implementedin di/dt estimator block, shown in FIG. 13 . The estimator blockcomprises two digital comparators (Comp 1 and Comp 2) and RS flip-flopelement. Both comparators provide transition pulses from “false” to“true” at the moments, when “Level” signal is equal to “6” (Comp 1) and“1” (Comp 2). These rising edges are detected by RS flip-flop, whichchanges its output state accordingly, providing a “true” signal at itsnon-inverting output Q when di/dt>0, and “false” signal when di/dt<0.

As it was mentioned earlier and presented in Table 1, there are manyswitching states available for each voltage level of nine-level ACibattery pack, except of ±4 VDC, when all intelligent battery modules areinvolved in providing a maximum positive or negative output voltage.Thus, there are following major tasks, which have to be resolvedcontrolling the current of the motor, taking into account thathysteresis “Level” and a sign of di/dt are already known parameters:

-   -   1) Based on the state of charge (SOC) of each intelligent        battery module, an identification of the intelligent battery        module which has to be switched repetitively for some period of        time to provide the required output voltage level and regulation        of output current. This identification methodology has to ensure        a balancing of the state of charges during an operation of the        ACi battery pack. When this is provided, the energy, stored in        batteries, or transferred from or to the motor, is equally        distributed among all intelligent battery modules. This is a        necessary condition of correct operation of ACi battery pack,        where each cell has to be designed for a specific temperature        profile of semiconductor switches based on their operational        regimes. This task is performed by SOC balancing block (see FIG.        11 ) in the method provided herein, and the functional diagram        of intelligent battery module rotation controller 600 as this        block's main component is presented in FIG. 12 .    -   2) For the intelligent battery module, identified by SOC        balancing block, a rotation of zero switching state. This        rotation provides a distribution of energy among the switches        within a specific module in operation. There are two possible        combinations of switching to provide a zero voltage at the        output of intelligent battery module, as shown in Table 1. The        rotation methodology alternates the switches used to provide a        zero voltage with every second positive or negative operational        level of the cell. In fact, as it will be shown in next section        of this document, this rotation reduces twice the switching        frequency of the switches in comparison with output voltage        frequency of the intelligent battery module and the entire ACi        battery pack. There are four rotation generator blocks 1001,        1002, 1003, and 1004 in the method provided herein for different        levels of output voltage from 0 VDC to 3 VDC, which are        presented in FIGS. 16A, 16B, 16C and 16D.

Each of four rotation generators in FIGS. 16A, 16B, 16C and 16Dcomprises: four digital comparators, one inverting element, four logicelements AND, two SR flip-flops Latch 1 and Latch 2 and two frequencydividers by 2. The structure and operational principle of all rotationgenerator blocks are the same; a difference is in the preset values ofdigital comparators only. In a 0 VDC rotation generator, when “di/dt”signal from di/dt estimator output is “true”, the comparator Comp1 willset SR flip-flop Latch 1 output at ‘true” when the “Level” signal isequal to “3”, which corresponds to +1 VDC of output voltage level.Another comparator Comp2, at positive di/dt will reset Latch 2, when the“Level” signal is equal to “2”, which corresponds to +0 VDC of outputvoltage level. In other words, a high level of pulse train at the outputof Latch 1 will correspond to +1 VDC voltage at the output of thenine-level converter, while its zero level will indicate +0 VDC voltagelevel (+0 indicates that 0 VDC level is following after and/or before+VDC level). Finally, the circuit included the frequency divider blockand logic element AND is intended to set the output signal Rot+0 VDC at“true” with a high level of Latch 1 output, which happens at +1 VDCoutput voltage level, and maintains this “true” signal until a secondtransition from +0 VDC to +1 VDC occurs. Such the output signal Rot+ 0VDC is used to alternate two possible zero state switching combinationsfor the intelligent battery module in operation of providing +1 VDCvoltage level. The same operational logic is behind the Rot −0 VDCsignal, which is generated by the same 0 VDC rotation generator toalternate two zero state switching combinations for the intelligentbattery module in operation of providing −1 VDC voltage level.

The intelligent battery module rotation controller 600 and SOC balancingblock provided herein for a multi-level hysteresis controller areexplained further. The detailed functional diagram of intelligentbattery module rotation controller is presented in FIG. 12 . The inputsof this block are the measured state of charges SOC1, SOC2, SOC3, andSOC4 from battery management systems (BMS) of all four intelligentbattery modules in one phase. The output signals are the numbers ofintelligent battery modules (from 1 to 4) with a maximum state of chargeSOCmax, minimum state of charge SOCmin, and then SOCrot3 and SOCrot4,distributed as follows: SOCmin<SOCrot4<SOCrot3<SOCmax. In the beginning,SOC1 and SOC2 are compared with each other and if their differenceΔSOC₁₂ is higher or lower than positive or negative threshold ofhysteresis block Hyst 1, then the output of this block is set to “1” or“0” respectively, otherwise it maintains its previously set value at theoutput. This threshold helps ignore a noise of certain level in thefeedback signal and regulates how often a rotation of intelligentbattery modules should occur. Based on Hyst 1 output signal, Switch 1choses a number of intelligent battery module (1 or 2) with a higher SOCand Switch 5 passes its corresponding SOC value to Sum 3, which comparesit with a lowest state of charge of SOC3 and SOC4, which go through thesame comparison technique. Thus, at the output of the intelligentbattery module rotation controller the intelligent battery modulesnumbers are distributed in accordance to their SOCs asSOCmin<SOCrot4<SOCrot3<SOCmax. Before going to rotation blocks signalsSOCmax and SOCmin are reassigned to SOCrot1 and SOCrot2 in SOC Balancingblock (see FIG. 11 ) taking into account a sign of reference currentI_(REF). If the current I_(REF) is positive, that corresponds to anenergy transferring from intelligent battery modules to the motor, thenthe intelligent battery module with a maximum SOC participates in arotation of all positive output voltage levels (but not at the sametime). This will cause a faster discharge of this intelligent batterymodule with a maximum SOC, because at positive output voltage andpositive load current there is only one way for energy to betransferred: from the intelligent battery module to the motor. At thesame time, at positive output current (or I_(REF)) the intelligentbattery module with a minimum SOC has to participate in providing thenegative output voltage levels only, to charge up its battery's voltageas soon as possible. That is because at positive load current butnegative output voltage of the output converter there is only onedirection for energy transfer: from the motor to batteries.

The 0 VDC rotation and 1 VDC rotation blocks are presented in FIGS. 14A,14B, 15A and 15B respectively. Let's describe +0 VDC rotation first.This block receives one control signal from intelligent battery moduleBalancing block SOCrot1, as well as one signal Rot +0 VDC from 0 VDCrotation generator, and provides the control signals for switchingelements of nine-level ACi battery pack for +0 VDC output voltage, where+0 means that 0 VDC level is following after and/or before +VDC level.The multiplexer Switch 1 chooses one of four different combinations ofswitching signals, based on input signal SOCrot1, indicating whichintelligent battery module is operating at the same time in providing+VDC output level. This means that a rotation of zero switching statehas to be performed for this specific intelligent battery module (withSOCrot1 number). The input signal Rot +0 VDC controls a sequence ofswitching between two possible zero states [1 1] and [0 0] for the sameintelligent battery module.

Block +1 VDC rotation has more complicated structure. Besides thecontrol signal Rot +1 VDC coming from 1 VDC rotation generator block, Itreceives two control signals SOCrot1 and SOCrot3 from SOC balancingblock. The first signal, SOC1rot, is used by multiplexer Switch 1 to setup a positive voltage at the output of intelligent battery module, whichnumber is specified by this signal. This can be done by providing theswitching combination [1 0] for that intelligent battery module. Allother three intelligent battery modules have to provide a zero switchingstate. If at the output of converter, the voltage is changing between +0VDC and +1 VDC, then the signal Rot+1 VDC is always “true” and there isno rotation of zero switching state for other three cells. If the outputvoltage is varying between +1 VDC and +2 VDC, then a rotation of zerostate has to be performed for only one specific intelligent batterymodule which is involved in producing of +2 VDC level. The input signalRot +1 VDC controls a sequence of switching between two possible zerostates [1 1] and [0 0] for that intelligent battery module.

The same principle of operation is valid for −0 VDC rotation and −1 VDCrotation, with only a difference in input signals SOCrot2, instead ofSOCrot1 and Rot−1 VDC, instead of Rot+1 VDC. The SOCrot3 signal, whichindicates a number of cell operating at both +2DC and −2 VDC levels,remains the same as for positive rotation blocks.

Blocks +2 VDC rotation and +3 VDC rotation have a complex structure withfour input signals, where three of them SOCrot1, SOCrot2 and SOCrot3 arecoming from SOC balancing block and one signal is either from 2 VDCrotation generator or 3 VDC rotation generator is intended to control asequence of changing between zero switching states for the specificintelligent battery module.

A detailed discussion regarding multi-level hysteresis control isprovided in U.S. Provisional Application No. 62/518,331, filed Jun. 12,2017, and U.S. Provisional Application No. 62/521,227, filed Jun. 16,2017, which applications are incorporated by reference as if set forthin full.

Local and Master ECUs Functions

The power electronics converters and local ECU 200, which manages theintelligent battery module 132 operation (see FIG. 5 ), works throughutilizing a state of charge (SOC) estimator to measure the initial SOCof the battery. A master control system (ECU) 210 receives this initialSOC data of all intelligent battery modules, as depicted in FIG. 17 (seealso FIG. 5 ), and classifies them.

A SOC balancing technique for multi-level hysteresis controller wasdescribed above. For multi-level PWM, this balancing methodology is asfollows: assuming all batteries are balanced before discharge, thestrongest battery is the one with the highest initial SOC and theweakest battery is the one with the lowest initial SOC when the ACibattery pack is fully charged.

Depending on this data, the master ECU 210 computes the correspondingswitching signals array that is necessary for proper operation of eachindividual intelligent battery module based on its battery capacity. Inother words, in order to balance the state of charge of the modules, theSOC of each module should be compared to the total SOC, which can becalculated as:

${SOC}_{tot} = \frac{{\sum}_{i = 1}^{n}{SOC}_{i}Q_{i}}{{\sum}_{i = 1}^{n}Q_{i}}$Where SOC_(i) and Q_(i)—individual SOC and capacity of i-th intelligentbattery module's battery and the difference along with a PI controllermay be used to control the modulation index (M) of each module. Notethat when the modules are charging the direction of the effect of SOCdifference must be reversed since in this case the module with higherSOC is expected to receive less energy compared to the other modules.

The local control system of the intelligent battery module 132 gets thisinformation and thus, there exists different switching signals arraysS_(1 . . . N) for each intelligent battery module which determines theindividual DC currents (I_(DC1), I_(DC2) . . . I_(DCN)) and DC-busvoltages (battery voltages V_(B1), V_(B2) . . . V_(BN)) of the system.In this way, the power management operates, and built-in powerelectronics unit manages the output power of each intelligent batterymodule autonomously. The strongest battery carries the highest currentand the weakest battery carries the least current so that the SOC of allthe batteries converge at a particular time.

Supercapacitor Module

The supercapacitor module 38 of intelligent battery module 132 (FIG. 5 )is connected in parallel to the main battery 32 and to the outputconverter 52. During acceleration, the capacitor voltage is allowed todischarge from full charge (50 Vdc) to approximately one-third of itsnominal voltage (17 Vdc), allowing it to deliver 11 kW of useful energy.This amount of energy allows taking 2.2 kW of power during 5 secondsform one intelligent battery module and 66 kW in total if 30 intelligentbattery modules are placed in an ACi battery pack, which is enough powerand time for a good acceleration without detriment to the battery life.During deceleration (regenerative braking), energy is recovered in asimilar way, charging back the supercapacitors.

When the vehicle accelerates, the battery delivers the amount of currentthe motor needs. If this current exceeds a current limit for thebattery, then the supercapacitor provides the difference. Theregenerative braking operation is similar. In this case, the motor worksas a generator delivering the recovered energy into the battery, but ifthe current injected exceeds the limit, then the DC-DC converter injectsthe excess into the supercapacitor.

The DC-DC converter works in two ways: Boost operation, used foracceleration which discharges the supercapacitor; and Buck operationused for deceleration (regenerative braking), which charges thesupercapacitor. During Boost operation (acceleration), the MOSFET S₂ isswitched on and off at a controlled duty cycle D, to transfer therequired amount of energy from the capacitor to the battery pack. WhenS₂ is ON, energy is taken from the supercapacitor and stored in theinductor L_(C). When S₂ is switched OFF, the energy stored in L_(C) istransferred into C_(F), through S₁, and then into the motor and/orbattery. During Buck operation, the converter introduces energy from thebattery to the supercapacitor. That operation is accomplished with acontrolled operation on S₁. When S₁ is switched ON, the energy goes fromthe battery to the supercapacitor, and L_(C) stores part of this energy.When S₁ is switched OFF, the remaining energy stored in L_(C) istransferred inside the supercapacitor through diode of S₂.

The battery as a primary energy source is the one with the highestenergy content and should therefore supply the average power needed bythe motor. The supercapacitor is a secondary energy source and assiststhe battery by providing/absorbing the momentary load power peaks.

The redundant structure of power flow management between two sources andmotor is presented in FIG. 18 . It has the advantage among other powercontrol methods since allows a complete decoupling between theelectrical characteristics (terminal voltage and current) of each sourceand those of the load. The power flow controller 1 receives a signal ofreference battery power flow P_(BATT, REF) from local ECU of intelligentbattery module. This signal is determined by main power managementcontroller located in a master ECU based on motor power P_(iBATTERY)requirements and SOC of individual intelligent battery module's battery.The power flow controller 1 estimates a maximum allowable batterycharge/discharge current and calculate a real permissible battery powerflow P_(BATT). This signal is compared with P_(iBATTERY) and theirdifference is applied to the power flow controller 2 as a signalP_(SC, REF). This controller calculates I_(SCM) current based onsupercapacitor voltage V_(SC) and determines the switching signals S₁and S₂ for buck/boost converter of Supercapacitor Module, which basicprinciples of operation are described above. Thus, P_(iBATTERY) flow isprovided by the output converter, P_(BATT) is estimated based on amaximum battery current and actual SOC and is ensured as a differencebetween P_(iBATTERY) and P_(SC), where the last one is managed bysupercapacitor module's converter.

Another important function performed by supercapacitor module is anactive filtering of the second-order current harmonic that appears inthe output converter's DC-current I_(DC) as result of the intrinsicpulsating power nature of a single-phase system. Considering V(t)_(OUT)and I(t)_(OUT) as the output voltage and current of intelligent batterymodule:V(t)_(OUT) =Vm _(OUT) cos(ωt)I(t)_(OUT) =Im _(OUT) cos(ωt+φ);The instantaneous input-output power balance of the intelligent batterymodule gives:

${P(t)}_{OUT} = {{{V(t)}_{OUT}{I(t)}_{OUT}} = {{\frac{1}{2}Vm_{OUT}{Im}_{OUT}{\cos(\varphi)}} + {\frac{1}{2}{Vm}_{OUT}{Im}_{OUT}{\cos\left( {{2\omega t} + \varphi} \right)}}}}$

The first constant term refers to the average power that is used tocharge/discharge the battery. The second oscillating term, however, doesnot contribute to the average battery SOC. This component has aconsiderable peak-to-peak value, which can reach up to two times thegrid current amplitude at a modulation index of unity. The second-ordercurrent component exhibits some disadvantages, e.g., increase of theinner battery resistive losses related to the resulting current RMSvalue as well as periodic change of the battery behavior.

The main waveforms for the active filtering case are shown in FIGS. 20Aand 20B. The supercapacitor acts as an active filter aiming at theelimination of the second-order harmonic in battery current I_(B).Before the compensations starts (before time moment t1), the current ofBattery I_(B) includes DC-component (I_(B)=130A) and second ordercomponent with an amplitude I_(2AC)=60A. Starting from the time momentt1, the supercapacitor module starts generating supercapacitor currentI_(SC), redirecting the second order harmonic of current I_(B) to thesupercapacitor (see FIG. 20B). This current I_(SC) has amplitude of mainharmonic equal to that of second order harmonic of I_(DC) current (seeFIG. 19 ), but with nearly opposite phase angle, in such a way that theresulting current in battery I_(B) includes either DC-component only ormostly DC-component with some significantly reduced AC-ripples, as shownin FIG. 20A.

At high RPMs a second-order current harmonic is suppressed significantlyby filtering capacitor C_(F) and operation of supercapacitor module isnot required.

FIG. 21 shows the single-phase nine-level four-quadrant intelligentbattery pack connected to a single-phase load, which is presented asRL-load. This system can be used for residential or commercial buildingsenergy storage and interruptible power supply systems.

FIG. 22 shows the three-phase intelligent battery pack comprising threenine-level two quadrant single-phase intellectual battery packsconnected to three-phase Switched-Reluctance Motor (SRM). A usage ofmulti-level hysteresis current controller and intelligent battery packallows improving efficiency and overall performance of SRM, as well assignificant reduction of torque ripples and acoustic noise.

In the foregoing description, numerous specific details are given toprovide a thorough understanding of the present embodiments. However, itwill be apparent that the present embodiments may be practiced withoutthese specific details. In order to increase clarity, some well-knowncircuits, system configurations, and process steps may not be describedin detail. In other instances, structures and devices are shown in ablock diagram form in order to avoid obscuring the invention.

The drawings showing embodiments of the present disclosure aresemi-diagrammatic and not to scale and, particularly, some of thedimensions are for the clarity of presentation and are shown exaggeratedin the drawing Figures.

Reference in the foregoing description to “one embodiment” or “anembodiment” or “certain embodiments” means that a particular feature,structure, or characteristic described in connection with the embodimentis included in at least one embodiment of the invention. The appearancesof the phrase “in one embodiment” in various places in the specificationare not necessarily all referring to the same embodiment.

Some portions of the detailed description are presented in terms ofalgorithms and symbolic representations of operations on data bitswithin a computer memory. These algorithmic descriptions andrepresentations are the methods used by those skilled in the dataprocessing arts to most effectively convey the substance of their workto others skilled in the art. An algorithm is here, and generally,conceived to be a self-consistent sequence of steps leading to a desiredresult. The steps are those requiring physical manipulations of physicalquantities. Usually, though not necessarily, these quantities take theform of electrical or magnetic signals capable of being stored,transferred, combined, compared or otherwise manipulated. It has provenconvenient at times, principally for reasons of common usage, to referto these signals as bits, values, elements, symbols, characters, terms,numbers or the like.

It should be borne in mind, however, that all of these and similar termsare to be associated with the appropriate physical quantities and aremerely convenient labels applied to these quantities. Unlessspecifically stated otherwise as apparent from the following disclosure,it is appreciated that throughout the disclosure terms such as“processing,” “computing,” “calculating,” “determining,” “displaying” orthe like, refer to the action and processes of a computer system, orsimilar electronic computing device, that manipulates and transformsdata represented as physical (electronic) quantities within the computersystem's registers and memories into other data similarly represented asphysical quantities within the computer system's memories or registersor other such information storage, transmission or display devices.

The present embodiments also relate to an apparatus for performing theoperations herein. This apparatus may be specially constructed for therequired purposes, or it may be a general-purpose computer selectivelyactivated or reconfigured by a computer program stored in the computer.The present embodiments may take the form of an entirely hardwareembodiment, an entirely software embodiment or an embodiment includingboth hardware and software elements. In one embodiment, the presentembodiments are implemented in software comprising instructions or datastored on a computer-readable storage medium, which includes but is notlimited to firmware, resident software, microcode or another method forstoring instructions for execution by a processor.

Furthermore, the present embodiments may take the form of a computerprogram product accessible from a computer-usable or computer-readablestorage medium providing program code for use by, or in connection with,a computer or any instruction execution system. For the purposes of thisdescription, a computer-usable or computer readable storage medium isany apparatus that can contain, store or transport the program for useby or in connection with the instruction execution system, apparatus ordevice. The computer-readable storage medium can be an electronic,magnetic, optical, electromagnetic, infrared, or semiconductor system(or apparatus or device) or a propagation medium. Examples of a tangiblecomputer-readable storage medium include, but are not limited to, asemiconductor or solid state memory, magnetic tape, a removable computerdiskette, a random access memory (RAM), a read-only memory (ROM), arigid magnetic disk, an optical disk, an EPROM, an EEPROM, a magneticcard or an optical card, or any type of computer-readable storage mediumsuitable for storing electronic instructions, and each coupled to acomputer system bus. Examples of optical disks include compact disk-readonly memory (CD-ROM), compact disk-read/write (CD-R/W) and digital videodisc (DVD).

To the extent the embodiments disclosed herein include or operate inassociation with memory, storage, and/or computer readable media, thenthat memory, storage, and/or computer readable media are non-transitory.Accordingly, to the extent that memory, storage, and/or computerreadable media are covered by one or more claims, then that memory,storage, and/or computer readable media is only non-transitory. Theterms “non-transitory” and “tangible” as used herein, are intended todescribe memory, storage, and/or computer readable media excludingpropagating electromagnetic signals, but are not intended to limit thetype of memory, storage, and/or computer readable media in terms of thepersistency of storage or otherwise. For example, “non-transitory”and/or “tangible” memory, storage, and/or computer readable mediaencompasses volatile and non-volatile media such as random access media(e.g., RAM, SRAM, DRAM, FRAM, etc.), read-only media (e.g., ROM, PROM,EPROM, EEPROM, flash, etc.) and combinations thereof (e.g., hybrid RAMand ROM, NVRAM, etc.) and later-developed variants thereof.

A data processing system suitable for storing and/or executing programcode includes at least one processor coupled directly or indirectly tomemory elements through a system bus. The memory elements may includelocal memory employed during actual execution of the program code, bulkstorage and cache memories providing temporary storage of at least someprogram code in order to reduce the number of times code must beretrieved from bulk storage during execution. In some embodiments,input/output (I/O) devices (such as keyboards, displays, pointingdevices or other devices configured to receive data or to present data)are coupled to the system either directly or through intervening I/Ocontrollers.

Network adapters may also be coupled to the data processing system toallow coupling to other data processing systems or remote printers orstorage devices through intervening private or public networks. Modems,cable modem and Ethernet cards are just examples of the currentlyavailable types of network adapters.

Finally, the methods and displays presented herein are not inherentlyrelated to any particular computer or other apparatus. Variousgeneral-purpose systems may be used with programs in accordance with theteachings herein, or it may prove convenient to construct morespecialized apparatus to perform the required method steps. The requiredstructure for a variety of these systems will appear from thedescription below. It will be appreciated that a variety of programminglanguages may be used to implement the teachings of the invention asdescribed herein.

The figures and the detailed description describe certain embodiments byway of illustration only. One skilled in the art will readily recognizefrom the foregoing description that alternative embodiments of thestructures and methods illustrated herein may be employed withoutdeparting from the principles described herein. Reference will now bemade in detail to several embodiments, examples of which are illustratedin the accompanying figures. It is noted that wherever practicablesimilar or like reference numbers may be used in the figures to indicatesimilar or like functionality.

Embodiments of the present disclosure are directed to aconverter-battery module architecture for an intelligent battery(iBattery) module used as a building unit of an intelligent battery packor system of intelligent battery packs. In embodiments, the iBatterymodule comprises a battery unit, a supercapacitor or ultra-capacitormodule unit and an output converter unit. In embodiments, a localcontrol unit of the iBattery module is configured to accept, process,and transmit signals, including, but not limited to, from temperature,voltage and current sensors, and the like, of the iBattery module;triggering and faults signals to and from semiconductor switches;voltages of elementary cells of the battery units and the supercapacitormodules. In embodiments, the local control system performs acommunication with and transmission of corresponding control signals toand from a master control unit of an intelligent alternating-currentbattery pack (ACi-Battery Pack) comprising a plurality of iBatterymodules.

Embodiments of the present disclosure are directed to an intelligentalternating-current battery pack (ACi-Battery Pack) comprising two ormore iBattery modules interconnected together in each phase. Inembodiments, the output voltage of any shape and frequency can begenerated at the outputs of ACi-Battery Pack as a superposition ofoutput voltages of individual iBattery modules.

Embodiments of the present disclosure are directed to a method ofmulti-level current hysteresis control to control the ACi-Battery Packto provide SOC and balancing between iBatteries in ACi-Battery Pack. Inembodiments, the method enables power sharing among all iBattery modulesin ACi-Battery Pack. In embodiments, the power sharing among alliBattery modules can be used to keep the SOCs of the battery modules ofiBatteries balanced at all times during operation, which ensures thatthe full capacity of each module is utilized regardless of possibledifferences in the capacities.

Embodiments of the present disclosure are directed to processes,methodologies and systems described herein relate to a motor vehicle anda stationary energy storage system.

Embodiments of the present disclosure are directed to an electricvehicle having a chassis, three or more wheels operably coupled to thechassis, one or more electric motors operably coupled to the three ormore wheels, one or more intelligent modular battery packs operablycoupled to the one or more motors, and a control system operably coupledto the one or more battery packs and the one or more motors.

In embodiments, the chassis is drivetrain-less. In embodiments, the oneor more motors are in-wheel motors.

In embodiments, the one or more intelligent modular battery packs havinga cascaded interconnected architecture.

In embodiments, the battery packs comprise a plurality of interconnectedintelligent battery modules.

In embodiments, the battery modules comprise an integrated combinationof a networked low voltage converter/controller with peer-to-peercommunication capability, embedded ultra-capacitor or super-capacitor, abattery management system, and serially connected set of individualcells.

In embodiments, the battery packs comprise a neural network comprising aplurality of interconnected intelligent battery modules.

In embodiments, the battery modules comprise an integrated combinationof a battery with a BMS, a supercapacitor module, and an outputconverter.

In embodiments, the supercapacitor module includes a bidirectional DC-DCconverter and a supercapacitor bank.

In embodiments, the output converter comprises a four-quadrant H-bridge.

In embodiments, the control system comprises a bi-directional multilevelcontroller.

In embodiments, the bi-directional multilevel controller is abi-directional multilevel hysteresis controller.

In embodiments, the bi-directional multilevel controller is combinedwith temperature sensors and networking interface logic.

In embodiments, the control system is configured to balance batteryutilization through individual switching of modules based on module age,thermal condition and performance characteristics.

In embodiments, the battery packs are switchable to a rectifier/chargeroperation.

Embodiments of the present disclosure are directed to an intelligentmodular battery pack comprising a cascaded architecture comprising aplurality of inter-connected intelligent battery modules.

In embodiments, the battery modules comprise an integrated combinationof a networked low voltage converter/controller with peer-to-peercommunication capability, embedded ultra-capacitor, battery managementsystem and serially connected set of individual cells.

In embodiments, the inter-connected intelligent battery modules comprisea neural network.

In embodiments, the battery modules comprise an integrated combinationof a battery with a BMS, a supercapacitor module, and an outputconverter.

In embodiments, the supercapacitor module includes a bidirectional DC-DCconverter and a supercapacitor bank.

In embodiments, the output converter comprises a four-quadrant H-bridge.

Embodiments of the present disclosure are directed to an intelligentbattery module comprising an integrated low voltage converter/controllerwith peer-to-peer communication capability, an embedded ultra-capacitor,a battery management system, and a plurality of serially connected setof individual cells.

Embodiments of the present disclosure are directed to an intelligentbattery module comprising a battery with an integrated BMS, asupercapacitor module operably coupled to the battery, and an outputconverter operably coupled to the battery and the supercapacitor module.

In embodiments, the supercapacitor module includes a bidirectional DC-DCconverter and a supercapacitor bank.

In embodiments, the output converter comprises a four-quadrant H-bridge.

All features, elements, components, functions, and steps described withrespect to any embodiment provided herein are intended to be freelycombinable and substitutable with those from any other embodiment. If acertain feature, element, component, function, or step is described withrespect to only one embodiment, then it should be understood that thatfeature, element, component, function, or step can be used with everyother embodiment described herein unless explicitly stated otherwise.This paragraph therefore serves as antecedent basis and written supportfor the introduction of claims, at any time, that combine features,elements, components, functions, and steps from different embodiments,or that substitute features, elements, components, functions, and stepsfrom one embodiment with those of another, even if the followingdescription does not explicitly state, in a particular instance, thatsuch combinations or substitutions are possible. Express recitation ofevery possible combination and substitution is overly burdensome,especially given that the permissibility of each and every suchcombination and substitution will be readily recognized by those ofordinary skill in the art upon reading this description.

In many instances, entities are described herein as being coupled toother entities. It should be understood that the terms “coupled” and“connected” or any of their forms are used interchangeably herein and,in both cases, are generic to the direct coupling of two entitieswithout any non-negligible e.g., parasitic intervening entities and theindirect coupling of two entities with one or more non-negligibleintervening entities. Where entities are shown as being directly coupledtogether, or described as coupled together without description of anyintervening entity, it should be understood that those entities can beindirectly coupled together as well unless the context clearly dictatesotherwise.

While the embodiments are susceptible to various modifications andalternative forms, specific examples thereof have been shown in thedrawings and are herein described in detail. It should be understood,however, that these embodiments are not to be limited to the particularform disclosed, but to the contrary, these embodiments are to cover allmodifications, equivalents, and alternatives falling within the spiritof the disclosure. Furthermore, any features, functions, steps, orelements of the embodiments may be recited in or added to the claims, aswell as negative limitations that define the inventive scope of theclaims by features, functions, steps, or elements that are not withinthat scope.

What is claimed is:
 1. A method of generating power for a load using amodular battery system that comprises converter modules arranged in aplurality of cascades, wherein each cascade comprises a plurality ofconverter modules, wherein the plurality of cascades together output ACvoltage signals of multiple phases, and wherein each converter modulecomprises a battery and a plurality of switches controllable toselectively output voltages from the converter module, the methodcomprising: sensing operating parameters about the batteries of theconverter modules, the operating parameters comprising temperatures ofthe batteries of the converter modules; generating, for each cascade,respective pulse width modulated (PWM) switching signals based at leaston the operating parameters about the batteries; and controlling theplurality of switches of the plurality of converter modules of eachcascade with the respective PWM switching signals such that each cascadeoutputs a single phase AC voltage signal comprising a superposition ofoutput voltages from each of the plurality of converter modules of thecascade; wherein control of the plurality of switches of the pluralityof converter modules of each cascade with the respective PWM switchingsignals balances a temperature of at least two batteries of theplurality of converter modules.
 2. The method of claim 1, furthercomprising: generating, for each cascade, at least one reference signal;and generating, for each cascade, carrier signals for the plurality ofconverter modules of the cascade, wherein each carrier signal is for adifferent converter module of the cascade and has a different phase thaneach other carrier signal.
 3. The method of claim 2, wherein: theplurality of converter modules of each cascade comprises S convertermodules; and the carrier signals each have a different phase separatedby 360°/2S.
 4. A method of generating power for a load using a modularbattery system that comprises converter modules arranged in a pluralityof cascades, wherein each cascade comprises a plurality of convertermodules, wherein the plurality of cascades together output AC voltagesignals of multiple phases, and wherein each converter module comprisesa battery and a plurality of switches controllable to selectively outputvoltages from the converter module, the method comprising: sensingoperating parameters about the batteries of the converter modules, theoperating parameters comprising temperatures of the batteries of theconverter modules; generating, for each cascade, respective pulse widthmodulated (PWM) switching signals based at least on the operatingparameters about the batteries; and controlling the plurality ofswitches of the plurality of converter modules of each cascade with therespective PWM switching signals such that each cascade outputs a singlephase AC voltage signal comprising a superposition of output voltagesfrom each of the plurality of converter modules of the cascade; whereinthe operating parameters comprise states of charge (SOC) of thebatteries, and wherein control of the plurality of switches of theplurality of converter modules of each cascade with the respective PWMswitching signals balances SOC of two or more batteries of the pluralityof converter modules.
 5. The method of claim 4, further comprising:generating, for each cascade, at least one reference signal; andgenerating, for each cascade, carrier signals for the plurality ofconverter modules of the cascade, wherein each carrier signal is for adifferent converter module of the cascade and has a different phase thaneach other carrier signal.
 6. The method of claim 4, wherein: theplurality of converter modules of each cascade comprises S convertermodules; and the carrier signals each have a different phase separatedby 360°/2S.
 7. The method of claim 6, wherein the plurality of cascadescomprises three cascades, the multiple phases comprise three phases, andthe motor load comprises a three phase motor.
 8. The method of claim 4,wherein the load comprises a motor load of an electric vehicle, themethod further comprising providing each single phase AC voltage signalto the motor load.
 9. The method of claim 1, wherein the load comprisesa motor load of an electric vehicle, the method further comprisingproviding each single phase AC voltage signal to the motor load.
 10. Themethod of claim 9, wherein the plurality of cascades comprises threecascades, the multiple phases comprise three phases, and the motor loadcomprises a three phase motor.
 11. A method of generating power for aload using a modular battery system that comprises converter modulesarranged in a plurality of cascades, wherein each cascade comprises aplurality of converter modules, wherein the plurality of cascadestogether output AC voltage signals of multiple phases, and wherein eachconverter module comprises a battery and a plurality of switchescontrollable to selectively output voltages from the converter module,the method comprising: sensing operating parameters about the batteriesof the converter modules, the operating parameters comprisingtemperatures of the batteries of the converter modules; generating, foreach cascade, respective pulse width modulated (PWM) switching signalsbased at least on the operating parameters about the batteries; andcontrolling the plurality of switches of the plurality of convertermodules of each cascade with the respective PWM switching signals suchthat each cascade outputs a single phase AC voltage signal comprising asuperposition of output voltages from each of the plurality of convertermodules of the cascade; wherein the battery of each converter module isa primary energy source, and each converter module further comprises asecondary energy source.
 12. The method of claim 11, wherein thesecondary energy source of each converter module comprises a capacitor,the method further comprising supplying power from each secondary energysource to supplement power supplied by each battery during accelerationof an electric vehicle.
 13. The method of claim 1, wherein the pluralityof converter modules of each cascade are coupled in series.
 14. Amodular battery system controllable to supply power to a load, themodular battery system comprising: converter modules arranged in aplurality of cascades, each cascade comprising a plurality of convertermodules, wherein the plurality of cascades together output AC voltagesignals of multiple phases, and wherein each converter module comprises:a battery; and a plurality of switches controllable to selectivelyoutput voltages from the converter module; a control system coupled withthe plurality of converter modules of each cascade and configured to:generate, for each cascade, respective pulse width modulated (PWM)switching signals based at least on the operating parameters about thebatteries, the operating parameters comprising temperatures of thebatteries of the plurality of converter modules; and control theplurality of switches of the plurality of converter modules of eachcascade with the respective PWM switching signals such that each cascadeoutputs a single phase AC voltage signal comprising a superposition ofoutput voltages from each of the plurality of converter modules of thecascade; wherein control of the plurality of switches of the pluralityof converter modules of each cascade with the respective PWM switchingsignals balances a temperature of at least two batteries of theplurality of converter modules.
 15. The system of claim 14, wherein thecontrol system is configured to: generate, for each cascade, at leastone reference signal; and generate, for each cascade, carrier signalsfor the plurality of converter modules of the cascade, wherein eachcarrier signal is for a different converter module of the cascade andhas a different phase than each other carrier signal.
 16. The system ofclaim 15, wherein: the plurality of converter modules of each cascadecomprises S converter modules; and the carrier signals each have adifferent phase separated by 360°/2S.
 17. A modular battery systemcontrollable to supply power to a load, the modular battery systemcomprising: converter modules arranged in a plurality of cascades, eachcascade comprising a plurality of converter modules, wherein theplurality of cascades together output AC voltage signals of multiplephases, and wherein each converter module comprises: a battery; and aplurality of switches controllable to selectively output voltages fromthe converter module; a control system coupled with the plurality ofconverter modules of each cascade and configured to: generate, for eachcascade, respective pulse width modulated (PWM) switching signals basedat least on operating parameters about the batteries, the operatingparameters comprising temperatures of the batteries of the plurality ofconverter modules; and control the plurality of switches of theplurality of converter modules of each cascade with the respective PWMswitching signals such that each cascade outputs a single phase ACvoltage signal comprising a superposition of output voltages from eachof the plurality of converter modules of the cascade; wherein theoperating parameters comprise states of charge (SOC) of the batteries,and wherein control of the plurality of switches of the plurality ofconverter modules of each cascade with the respective PWM switchingsignals balances SOC of two or more batteries of the plurality ofconverter modules.
 18. The system of claim 17, wherein control of theplurality of switches of the plurality of converter modules of eachcascade with the respective PWM switching signals balances a temperatureof at least two batteries of the plurality of converter modules.
 19. Thesystem of claim 17, wherein the control system is configured to:generate, for each cascade, at least one reference signal; and generate,for each cascade, carrier signals for the plurality of converter modulesof the cascade, wherein each carrier signal is for a different convertermodule of the cascade and has a different phase than each other carriersignal.
 20. The system of claim 17, wherein the plurality of cascadescomprises three cascades, the multiple phases comprise three phases, andthe load comprises a three phase motor of an electric vehicle.
 21. Thesystem of claim 14, wherein the plurality of cascades comprises threecascades, the multiple phases comprise three phases, and the loadcomprises a three phase motor of an electric vehicle.
 22. A modularbattery system controllable to supply power to a load, the modularbattery system comprising: converter modules arranged in a plurality ofcascades, each cascade comprising a plurality of converter modules,wherein the plurality of cascades together output AC voltage signals ofmultiple phases, and wherein each converter module comprises: a battery;and a plurality of switches controllable to selectively output voltagesfrom the converter module; a control system coupled with the pluralityof converter modules of each cascade and configured to: generate, foreach cascade, respective pulse width modulated (PWM) switching signalsbased at least on operating parameters about the batteries, theoperating parameters comprising temperatures of the batteries of theplurality of converter modules; and control the plurality of switches ofthe plurality of converter modules of each cascade with the respectivePWM switching signals such that each cascade outputs a single phase ACvoltage signal comprising a superposition of output voltages from eachof the plurality of converter modules of the cascade; wherein eachconverter module comprises two energy sources, and wherein the twoenergy sources of each converter module comprises the battery of theconverter module.
 23. The system of claim 22, wherein the two energysources of each converter module comprises a capacitor, and wherein thesystem is configured to supply power from each capacitor to supplementpower supplied by each battery during acceleration of an electricvehicle propelled by the three phase motor.
 24. A method of generatingpower for a load using a modular battery system that comprises convertermodules arranged in a plurality of cascades, each cascade comprising aplurality of converter modules, wherein the plurality of cascadestogether output AC voltage signals of multiple phases, and wherein eachconverter module comprises a battery and a plurality of switchescontrollable to selectively output voltages from the converter module,the method comprising: receiving, by a master control unit and fromlocal control units of the modular battery pack system, operatingparameters about the batteries of the converter modules, the operatingparameters comprising temperatures of the batteries of the convertermodules; for each cascade: generating, by the master control unit, atleast one reference signal; generating carrier signals for the pluralityof converter modules of the cascade, wherein each carrier signal is fora different converter module of the cascade and has a different phasethan each other carrier signal; and providing, by the master controlunit, the at least one reference signal to the local control units;generating, by the local control units, respective pulse width modulated(PWM) switching signals for each cascade based at least on informationrepresentative of the operating parameters about the batteries; andcontrolling, by the local control units, the plurality of switches ofthe plurality of converter modules of each cascade with the respectivePWM switching signals such that each cascade outputs a single phase ACvoltage signal comprising a superposition of output voltages from eachof the plurality of converter modules of the cascade.
 25. The method ofclaim 24, wherein: the plurality of converter modules of each cascadecomprises S converter modules; and the carrier signals each have adifferent phase separated by 360°/2S.
 26. The method of claim 24,wherein control of the plurality of switches of the plurality ofconverter modules of each cascade with the respective PWM switchingsignals balances a temperature of at least two batteries of theplurality of converter modules.
 27. The method of claim 24, wherein theoperating parameters comprise states of charge (SOC) of the batteries,and wherein control of the plurality of switches of the plurality ofconverter modules of each cascade with the respective PWM switchingsignals balances SOC of two or more batteries of the plurality ofconverter modules.
 28. The method of claim 24, wherein the loadcomprises a motor load of an electric vehicle, the method furthercomprising providing each single phase AC voltage signal to the motorload.
 29. The method of claim 28, wherein the plurality of cascadescomprises three cascades, the multiple phases comprise three phases, andthe motor load comprises a three phase motor.
 30. The method of claim28, wherein each converter module comprises two energy sources, a firstone of the two energy sources of each converter module being the batteryof the converter module.
 31. The method of claim 30, wherein a secondone of the two energy sources of each converter module is a capacitor,the method further comprising supplying power from each capacitor tosupplement power supplied by each battery during acceleration of theelectric vehicle.
 32. A modular battery system controllable to supplypower to a load, the modular battery system comprising: convertermodules arranged in a plurality of cascades, each cascade comprising aplurality of converter modules, wherein the plurality of cascadestogether output AC voltage signals of multiple phases, and wherein eachconverter module comprises: a battery; and a plurality of switchescontrollable to selectively output voltages from the converter module;and a control system comprising a master control unit and local controlunits, wherein the control system is configured to: communicate, fromthe local control units to the master control unit, operating parametersabout the batteries of the converter modules, the operating parameterscomprising temperatures of the batteries of the converter modules; andfor each cascade, the control system is configured to: generate at leastone reference signal; generate carrier signals for the plurality ofconverter modules of the cascade, wherein each carrier signal is for adifferent converter module of the cascade and has a different phase thaneach other carrier signal; and communicate the at least one referencesignal from the master control unit to the local control units; generatefor each cascade, respective pulse width modulated (PWM) switchingsignals based at least on information representative of the operatingparameters about the batteries; and control the plurality of switches ofthe plurality of converter modules of each cascade with the respectivePWM switching signals such that each cascade outputs a single phase ACvoltage signal comprising a superposition of output voltages from eachof the plurality of converter modules of the cascade.
 33. The system ofclaim 32, wherein control of the plurality of switches of the pluralityof converter modules of each cascade with the respective PWM switchingsignals balances a temperature of at least two batteries of theplurality of converter modules.
 34. The system of claim 32, wherein theload comprises a motor load of an electric vehicle, and wherein eachcascade outputs the single phase AC voltage signal to the motor load.35. The system of claim 32, wherein the plurality of cascades comprisesthree cascades, the multiple phases comprises three phases, and themotor load comprises a three phase motor.
 36. The system of claim 32,wherein the operating parameters comprise states of charge (SOC) of thebatteries, and wherein control of the plurality of switches of theplurality of converter modules of each cascade with the respective PWMswitching signals balances SOC of two or more batteries of the pluralityof converter modules.